This study will examine whether interleukin-2 (IL-2) plus antiretroviral therapy (ART) slows HIV disease progression in patients with low CD4+ T cell counts compared with patients taking ART alone. CD4+ T cells are a subset of lymphocytes-white blood cells that are part of the body's immune system. IL-2 is a protein that is naturally produced by lymphocytes. Given in intermittent cycles, IL-2 can raise CD4+ T cell counts in some HIV-infected patients taking antiretroviral drugs. This study will examine whether the increase in CD4+ T cells lowers the risk of AIDS-related illnesses and death.